The present invention relates to a method of forming groups of cigarettes.
Groups of cigarettes, each normally comprising three superimposed layers of cigarettes arranged in a five-spot pattern, are known to be formed by feeding a forming pocket in a given direction along a forming path extending through three unloading stations, at each of which the pocket is supplied with a respective layer by a respective transfer device located between the path and a cigarette hopper.
Each pocket is normally defined by a bottom wall, and by a front and rear wall crosswise to the bottom wall and comprising respective longitudinal projections for engaging respective cavities defined by the outermost cigarettes in the intermediate layer and the adjacent outermost cigarettes in the top and bottom layers, to retain the cigarettes in position inside the pocket. The transfer device at each unloading station normally comprises a lobed drum rotating about a respective horizontal axis crosswise to the traveling direction of the forming pocket, and comprising a number of lobes, the free end of each of which comprises a respective transfer seat for transferring a respective layer of cigarettes; and each seat is fed through the respective unloading station in time with a forming pocket, and engages the pocket to deposit the respective layer.
The above method involves several drawbacks. Firstly, the longitudinal projections in the forming pocket allow only partial insertion of each lobe to deposit the respective layer, so that the cigarettes are dropped from the lobe into the pocket. Secondly, being spaced relatively far apart in the transfer seat, the cigarettes must be compacted inside the forming pocket by compacting devices along the forming path to obtain groups of cigarettes suitable for wrapping.